Photographic-printing process.



J. 'E. THORNTON.

PHO'TOGRAPHI C PRINTING PROCESS.

APPLICATION FILED JUNE 30.1915.

1,288',753. I Patented Dec. 24,1918.

2 SHEETS-SHEET 1 Fig.2.

- Fig.5.

MW A 5 7 UNITED sTATEs PATENT onnron.

JOHN EDWARD THORNTON, or WEST HAMISTEAD, Lonnon, ENGLAND, nssrenon' ToJOHN ownnn onnrnn, or MANCHESTER, ENQLAND.

PHOTOGRAPHIC-PRIHTING PROCESS.

To all wh m it may concern:

Be it known that I, JOHN Enwnnn THORN- TON, a British subject, residing,at West Hampstead, London, England, have invented certain new and usefulImprovements in and Relating to Photographic-Printing Processes, ofwhich the following is a specification.

- This invention relates to the manufacture or productionofcinematograph films upon a bichromated colloid or upon a similar slowprinting surface, and is specially 1ntended for color printing where twoor more colors are superimposed, though it can be used forsingle colorwork if desired. It forms an improvement upon the following applicationsrecently filed by me in relation to this art; 733,633, filed November26, 1912; 745,724, filed February 1,1913; 745,725, filed February 1,1913;

772,440, filed June 7,1913; 38,016, filed July IIn some of thoseinventions, for example, United States applicationsSerial Nos. 760200and 772440, superimposed prints in different colors are made fromcontinuous duated negatives. upon material sen tone a sitizegf withbichromated colloids. Such prints may be developed from the front bystainmg with suitable dyes of the type that only stain soft gelatin anddo not stain the The purpose of this in'vention'is to provide animproved process by which films-to' the colloid of which dye or pigmentis added before rinting-are printed from the front, and eveloped fromthe front, without the necessity for any transfer or" after staining,

thereby securing greater simplicity and umformity than is possible whenthe coloring.

Specification of Letters Patent. Application filed June a. 1915. Serialm. 37,328.

760,200, filed April 10, 1913;

print; and

'bumen, gum,

Petented Dec. 24,1913.

matter or dye is added by means of developmentor staining afterprinting.

In the accompanying drawing Figure 1 is a perspective view of the filmand sensitized layer; i

Fig. 2 is a face view or plan of the film with a sensitized layer oneach side thereof;

.Fig. 3 represents a longitudinal section of the film and the sensitizedlayers on opposite sides thereof.

Fig. 4 is a diagrammatic view showing the method'of producing a positiveprint from a dot negative.

Fig. 5 represents a cross-section of the print obtained from the dotnegative.

Fig. 6 is a diagrammatic view showing a method of obtaining a dotnegative such as that shown in Fig. 4.

'- Fig. 57 is a diagrammatic view showing the method of arranging thedots indifferent positio'n's" inthe successive pictures of the finalFig. .8 is a diagrammatic yiew showing the relative positions of thedots of the pictures when projected in succession upon a screen. I

In carrying out the invention the film or othersupport 1 is first coatedwith a sensitized colloid 2such as gelatin, fish glue, al-

or mixtures thereof, -'in which igment or elsedg e of the desired colorhas con incorporate The sensitized film is exposed from the front forthe requisite period of time to print under a screen printing through tothe base, negative 6 of the special type hereinafter described, thendeveloped, washed, and dried.

If the colloid be gelatin, hot water is used for development; and if itbe fish glue, albumen or gum, cold water is used for development.

The development. is rendered capable of accomplishment from the front ofthe sensitized colloid. 2 (Fig. 4) and a sharp carbon print thusobtained because of'the breaking up of the image into a large number ofvery fine dots (say) about forty thousand to the s'quare'inch) y the useof a screen printing negative6 known-as a' process negative in whichthe-image is composed of a similar number of fine dots or lines, suchnegatives being used for halftone block making and other .well knownvphoto-mechanical processes. Fig. 4 shows diagrammatically the I ness ininverse ratio to that of the negative,

and the whole of the dots composing the image are insoluble from back tofront, the

soluble portions having been dissolved and washed away duringdevelopment.

By using such a negative the light is obstructed by the lines or dotsand the image is broken up into non-continuous blacks and half-tones,the tones being of uniform density and varying in area, instead of theregular graduated tones of varying density that would be obtained byusing a graduated continuous tone negative.

The efiect of this is to leave the bichromated colloid in the form ofhaving unprinted spaces that dissolve completely away duringdevelopment, leaving intervening parts composed of insoluble colloid(containing pigment or dye) extending right through from the front tothe base which stand up as lines or dots owing to the light which passesthrough the transparent spaces between the dots of the negative,penetrating through to the base supporting the colloid film, and therebyrendering it insoluble so that the pigment or dye is locked up in theinsoluble portions of colloid.

The resultant image is one having a somewhat grainy appearance, but ismore transparent than one in continuous graduated tones.

The screen printing negative 6 which is used in accordance with thepresent invention is made, as shown diagrammatically in Fig. 6, byplacing acontinuous tone positive cinematograph film 8, which latter ismade by contact from the original continuous tone negative, in front ofa powerful light 9 and placing behind such film a sensitive silverbromid film 10, a dot screen 11 being interposed between the two films.

Upon developing the sensitive film so exposed the screen negative 6 willresult bearing a series of images that are counterparts of the originalexcept that they consist of dots or grain varying in .size andcloseness, thus producing a picture in broken tones instead ofcontinuoustones.

This film is used as a negative for producing the required cinematographfilms.

By suitable modifications of screen, diaphragm, light distances, andexposure, a variety of efi'ects are obtainable according to character ofsubject and other governing factors.

For cinematograph films in two or more colors, (multi-colors after thestyle of the Lumiere autochrome. screen plates or the Sanger-Shepherdsuperimposed prints), the positive film is sensitized, printed anddeveloped, two, three or four times, each time from one of these specialscreen negatives according to number of colors required, eachsensitizing and printing being superimposed upon the preceding one asset forth in my pending applications Serial Nos. 760200 and The specialbroken tone or screen printing negatives for such color Work may be madein the manner already described, either from continuous tone negatives,each of which represents one color only, out of the two, three or fourcolors; or they may be made from a multi-color negative of the Lumierefilm; but where two prints are made on opposite sides of the same pieceof film they ma be sensitized together and printed simultaneously.

By coating two layers of sensitized emulsion in two colors on one sideof thefilm such as red and green, one on top of the other, and thenexposing through a red filter, and then giving a second exposure througha green filter, two colors may be printed immediately one after theother, and developmentof the two proceed simultaneously. In this case atwo-colorfinished pic-' ture is obtained at one complete operation.

The same efi'ect may be got if the two layers of colored sensitizedemulsion 3 and 4 are coated upon opposite sides of the film 5, as shownin Figs. '2 and 3.

By coating the other side of the film with a third layer of coloredsensitized emulsion a three color picture is obtained.

And b coating the second side of the filmthe reproduced grainy or screenprinting negative, as shown diagrammatically in Fig. 7 so that the linesor dots of each picture i come in a different place on the projectionthe relative ppsitions of the dots of the successive pictures asprojected onto the screen being shown diagrammatically in Fig. 8.

It will be understood that the term negative applies to the transparentcliche used in printing the final print, but it may be either a negativeor a positive according to the'character of print desired.

The image may be converted into and printed in the form of fine linesinstead of fine dots if preferred.

mm I claim as my inventionand desire to protect by Letters Patent isc 1. In the production of a cinematograph films by the carbonprocessupon a colored sensitized colloid, the improved process which comprisespreparing from an ordinary cinematograph full tone negative a reproducednegative of broken tones or dots and printing through such reproducednega'-' tive and through'said colored sensitized colloid from front toback to produce a final .print composed of dotsof colo'red colloid allof the same height or thickness but varying in theirarea or distance ofseparation which dots have been rendered insoluble.

2. The process of producing cinematograph films from a negative taken bya camera which consists in printing from the negative on to a sensitizedfilm to produce a positive, photographing such posltive through a screenonto another film to pro\ duce a screen printing negative and finallyprinting therefrpm, on to the front and through to the back of a coloredsensitized film and developing same from the front.

3. In the process of roducing multi-color cinematograph films bysuperimposing a plurality of printings of section color pic tures on thesame film, preparing each color which the film is composed, said dotsbeing\ of uniform depth or height, the area of or distance between thedots varying to give varying gradation oflight and shade to differentparts of the picture and which dots are obtained through theintervention of a screen. 4

5. A cinematograph film having a series of. pictures superimposedthereon, each picture being represented in dots of gelatin of which thefilm is composed, the dots being of uniform depth or height and the areaof or distance between the dots varying to give varying gradation oflightand shade toeach picture. 7 p

In testimony whereof I have hereunto set my hand in presence of asubscribing Witness.

- JOHN Witness:

I. OWDEN OBRIEN.

EDWARD THORNTON.

